Effects of elevated CO2 on photoinhibition of strawberry leaves under different nitrogen levels
Xu, K.; Guo, Y-ping.; Zhang, S-long.; Wu, H-min.
Ying Yong Sheng Tai Xue Bao 18(1): 87-93
2007
ISSN/ISBN: 1001-9332 PMID: 17396505 Document Number: 613012
By using PAM-2000 portable chlorophyll fluorometer and HCM-1000 photosynthesis measurement system, this paper measured the initial fluorescence (F-o), maximal photochemical efficiency of PSII (F-v/F-m), maximal fluorescence (F-m), amount of inactive PS II reaction centers F-i-F-0 proportion of Q(B)-non-reducing PS II reaction centers [(F-i-F-0)/(F-p-F-0)] and net photosynthetic rate (P-n) of strawberry leaves under conditions of elevated CO2 (700 mu l center dot L-1) and ambient CO2 (390 mu l center dot L-1) at three levels of nitrogen application (12, 4 and 0.4 mmol center dot L-1). The results showed that there was a significant joint effect between CO2 and N on the photoinhibition of strawberry leaves. Under elevated CO2 condition, the P-n in treatment 12 mmol N center dot L-1 increased by 62.7%, while that in treatments 4 and 0.4 mmol N center dot L-1 decreased by 7.4% and 21.3%, respectively. When exposed to high light and subsequently recovered in dark for 4 hours, the strawberry leaves in treatment 12 mmol N center dot L-1 showed less changes of F-m and F-v/F-m in elevated CO2 than in ambient CO2, while those in treatments 4 and 0.4 mmol N center dot L-1 were in adverse, suggesting that for the strawberry leaves in elevated CO2, nitrogen deficiency could result in an acclimatized decrease of photosynthesis and an increase of photoinhibition.